Diffuse melanosis secondary to metastatic melanoma in a Nelore bull

Abstract

We report a case of diffuse melanosis secondary to metastatic malignant melanoma in a Nelore bull. Clinical signs included isolation from the herd, epistaxis, hyperthermia, pale ocular membranes, mucoid diarrhea and dark urine. Despite anti-inflammatory and antibiotic therapy, the bull died 45 days after the onset of the clinical signs. The most striking lesion was diffuse black discoloration to the visceral organs including liver, spleen, lungs, lymph nodes, and kidneys; all these affect organs were moderately enlarged”. The urine was black. Histologically, 50-80% of the parenchyma of the liver, spleen and lymph nodes was obliterated by aggregates of melanin-loaded neoplastic melanocytes. Those neoplastic cells also occurred within capillaries of the liver, spleen, lymph nodes, urinary bladder, lungs and kidneys. Immunohistochemistry of neoplastic melanocytes was positive for Melan A and PNL2 markers. Abundant brown to black pigment was found in melanophages in the lungs, confirmed by IBA1 immunohistochemistry.

Extracutaneous Melanotic Melanoma with Nervous System Involvement in a Buffalo (Bubalus bubalis)

“…In bovine species, cases of melanoma have been reported, affecting the skin [ 27 ], lymph nodes [ 18 ], oral cavity [ 18 ], heart [ 18 , 27 ], lung [ 18 , 19 ], liver [ 18 , 19 , 27 ], mammary glands [ 18 ], hooves [ 21 ], and spleen and kidneys [ 19 ].…”

“…Melanoma is common in humans and dogs, but rare in animals reared for meat. In Brazil, melanoma has been reported in goats [ 13 , 14 ], pigs [ 15 ], and rabbits [ 16 ], and is relatively common in grey-haired horses [ 17 ], and cattle [ 18 , 19 ]. It has also been reported in cattle in India [ 20 , 21 ], the United States [ 22 ], and Turkey [ 23 ].…”